Catalytic synthesis of methane.



F. BEDFORD & c. E. WILLIAMS.

CATALYTIC SYNTHESIS OF METHANE.

APPLICATION FILED FEB. 25, 1910.

Patented Jan. 31, 1911.

. contain termed, impurities-such as sulfureted hy- FRED BEDFOBD ANDCHARLES E.

WILLIAMS, OF SLEAFORD, ENGLAND, 'ASSIGNORS T0 CEDFORD GAS PROCESSCOMPANY, OF LONDON, ENGLAND.

CATALYTIC SYNTHESIS OF METHANE.

Specification of Letters Patent.

Application filed February 25, 1910. Serial No. 546,016.

To ailwhom it may concern:

Be it lmown that we, FRED Bnnronn, Ph.

1)., B. So. Lond, and CHARLES EDWARD VVI'L- I LIAMS, subjects of theKing of Great Britain and Ireland, and residing at Sleaford, in thecounty of Lincoln, England, have invented certain new and usefulImprovements in and Connected with the Catalytic Synthesis of Methane,of which the following is a specification.

This invention relates to an improved process for the catalyticsynthesis of methane.

or a mixture of methane with other gases.

7 The value of ordinary coal gas is due to the large percentage ofmethane contained therein, and attempts have been made to producemethane synthetically from carbon oxidsby the action of hydrogen in thepresence of finelydivided nickel, the function of the latter simplycatalytic. The re actions which take place may be represented by theequations This catalytic reaction proceeds smoothly.

sufficient quantity as demanded by the above equations. If,'howeveig'the reacting gases cei'taln substances hereiuafter drogen,carbon disulfid, mercaptanand sulfur compounds in general, even If onlyin 7 very minute quantities,the nickel very soon loses its activity. Inorder, therefore, to preserve the activity of the nickel, it is es- 4sential that the impurities invariably present In commercial gases becarefully removed before the latter are allowed to come in contact withthe catalytic nickel. Various processes have been proposed for theremoval of the Impurities. am all commercial gases obtained-by 1 coaland containing hydrogen an caon monoxid are deficient in hydrogen.Various methods have been pre- 7 posed-for the removal of the sulfurimpurities, and for obtaining carbon monoxid and .hydrogen intlie properrelative quantities, either by varying the mode of manufacture of thegases or by adding hydrogen. Some of these methods have depended on thecoolingof the gases to a degree sutficient only to .liquefythem ,with aview to the separation A of certainpf the-constituents. But none of tionof methane,

these processes have been so far commercially successful.

The object of this invention is to provide Patented Jan. 31, 1911.

a process by which the sulfur impurities may 7 be effectually removedand at the same time the cheapest of the commercial gases of the type of.Mond gas and Duff gas and the like may be commercially treated for theproducwithout there being any need to modify their process ofmanufacture. In carrying out this process the mixture of gases (whichshould be first freed from carbon dioxid) is cooled to the degreenecessaryin order to get the sulfur impurities into a solid form'havinglittle or no vapor tension 'the'hydrogen passing off as a gas and beingcollected while the carbon monoxid, nitro-- gen, and methane will beliquid or solid. On allowing this latter mixture to eva orat carbonmonoxid and nitrogen distil o5 first and are effectually separated fromthe sulfur impurities. After this distillation processa certain quantitof the carbon monoxid obtained is mixed with the hydrogen so that thehydrogen and carbon monoxid are in the required proportions. Thismixture is passed over nickel in the known manner. There should alwaysbe an excess of hydrogen over the theoretical quantity in order toprevent local heating of the metal. The amount of this excess depends onvarious circumstances, suchas the'spced at which the gaseous mixture ispassed. over the metal, and if nitro-v gen is present this acts as adiluent and assists in preventing local heating, and a To illustrateone. mode of carrying out the invention,

pare methane synthetically from. a Mond.

gas of the following approximate composition:-

Hydrogen 28. 0% Carbon monoxid 11. 0% Carbon dioxid t 16; 0%

Methane L 2. 0% Nitrogen 43. 0%

Thecarbon dioxid is first 'removed in any known manner, for example, byabsorption in a solution of movalbein'g desirable to prevent thecloggang of the apparatus by the carbon dioxid.

-The residual mixture is passed through a.

cooling apparatus adapted to cool it .to about i suppose it be requiredto presmaller excess of hydrogen may be usedthan would otherwise benecessary.

sodium carbonate, such re-- fied gas is drawn from the tower ethroug'hter this cooling process the hydrogen passes ofi as a gas, carrying withit small quantities only of carbon monoxid and nitrogen,

but leaving behind it the bulk of these gases with the methane andallthe sulfur impurities in the solid form that were present in thecommercial gas. On evaporating the mixture left after the removal of thehydrogen, the carbon monoxid and nitrogen distil off first, and thesemay be separated by known means, for example, by absorption of thecarbon monoxid by means of cnprous chlorid solution, from which thecarbon monoxid can be again obtained by evaporation. A certain quantityof the carbon monoxid thus obtained is mixed with the hydrogen so thatthese two gases are present in the required quantities and the mixtureentirelyfreed from the impurities which were present in the commercialgas, is passed over heated finely divided'nickel. By separating out theimpurities as above described, the life of the catalytic nickel isconsiderably prolonged. a

The'accompa nying drawing illustrates one convenient form of apparatusfor carrying out the process according to the present invention and inthe following description it willbe assumed that it is' desired tosynthesize methane from water gas. I

. Water gas, produced in any usual manner, 1s passed lnto the gas-holdera, which may .be of any convenient construction. From the gasometer athe crude water gas is drawn by means of a pump 6, through a. pair oftowers ,0, d; containing slaked lime placed upon baflies or perforatedplates and thence through a third tower e containing.

calcium chlorid, the function of the latter bemg to remove the carbondioxid from. the gas. A sample of the as, after passing through thetower e woul be found to give no turbidity with 'baryta water nor wouldit turn. lead acetate paper'brown, but a 'test with heated. finelydivided nickel. would prove that the purification thus far carried outwas utterly inadequate, as with even the mlnutest'traces of sulfur imurities in the gas would be sutlicient to kill the catalytic activlty ofthe nickel. The partially purithe pipe- 7 by the pump 1) and forced outthrough the plpe g into one of the wellknown liquefiers h where-theseparation of the hydrogen from the carbon monoxid takes place, thelatter liquefying and carrying down with it in the solid form the minutetrace of impurities which would otherwise be detrimental to the nickel.The hydrogen which remains in the gaseous state,'is led off into the,gas holder 2'. .The liquid carbon .synthesis of met ane.

The mixture of hydrogen, car

monoxid in the liquefier his allowed toboil off into the gas-holder. kat such a rate that the temperature of h is never allowed torise above-180 C. This is accomplished by never allowing all the carbon monoxid toevaporate. By these means all the deleterious impurities are held backin the lique: fier h. The inlets to the gas mixer Z are so adjusted thatthe hydrogen and carbon monoxid flowing therethrough from the gas liolders 2' and 7: are adjusted in the correct proportions demanded bytheory, that is,

in the proportion of not less than three to one. This mixture thenleaves the gas mixer Z- and is made to pass througha tower m containingfinely divided nickel and heated by means of an oil bath or othersuitable means to a temperature of about 250- C. This last step resultsinthe transformation of the mixture of hydrogen and carbon 1no-. noxidinto methane, the latter beingtcollected in the gas holder n where itmay be stored for further use or whence it may be directly drawn olf ifrequired. I

The series of operations for the synthesizing of Mond gas is similar tothose described for water 'gas with the exception that it is advisableto substitute iron hydroxid for 7 slaked lime in one of the towers ,0,I. On fractionating the Mond gas by .means of' the liquefier h, thehydrogen is again collected in the gas holder 2' and a mlxture of wheretheoriginal gas contains nitrogen, the mixer l is so adjusted that themixture of carbon monoxid and nitrogen contains the requisite quantityof carbon monoxid. -The final gas after passing through the towcrm is amixture of methane and nitrogen, whicl'iy-li of liquid air in such amanner that the impurities separate out ingthe solid form possessinlittle or no. apor tension and. that the w ole of the ca bon monoxiddoes not become liquid, but the hydro-gen retains the requisite amountof carbon monoxid for the This can be effected by regulating thepressure at which the fractional separation by coolin takes place.

on monoxid and nitrogen, freed from impurities by the cooling, is passedover heated finely divided nickel, a mixture of methane and nitrogenbeing thus formed. The nitrogen can be separated out by subjecting themixture toa temperature of about -180 0., the nltrogen remaining as agas and the methane liquefying. The nitrogen mayalso besep arated by anyother known means.

carbon monoxid and nitrogen will be 001- 'lected in is. In this case, asin all cases It is" to be noted that nitrogen is 'not an impurity in thesense hereinbefore referred to and it is immaterial, so far as the cata; lytic activity of the nickel is concerned, whether it is present ornot during the catalytic reaction. In some cases as for. in-

stance in the case of coal gas it is advantageous before the gases arecooled to partly purify them, e. 9., with iron hydroxid.

Having now described our invention what we claim as new and .desire tosecure by- Let ters Patent is v 1. A process for the catalytic synthesisof methane from a commercial-gas containing hydrogen and carbon monoxidcompris"v ing cooling the commercial gas to such a degree that theimpurities separate out in the solid form possessing little or no vaportension and passing the purified commercial gas into contact with aheated catalytic substance, for the: purpose set forth.

2. A process for the catalytic synthesis of methane from a commercialgas containing hydrogen and carbon monoxid comprisingsubjectingthefcommercial gas to a cooling process for the purpose of separating.out the impurities in the solid form possessing little or no vaportension, and in such a manner that the hydrogen retains the requisitequantity of carbon monoxid, and pass ing the mixture into contact with aheated catalytic substance, fo'r the purpose set forth.

3. A process for the catalytic synthesis methane from a commercial gascontaining hydrogen and carbon monoxid-comprising subjecting thecommercial gas to accol- 4*. A process for the catalytic synthesis" ofmethane from a commercial gas contain: ing hydrogen and carbon monoxidcomprising subjecting the commercial gas to a cooling process for. thepurposeof separating out the impurities in the solid formpossessinglittle or no 'vapor tension, and in such a manner that the hydrogenretains the requisite quantity of carbon monoxid, passingthe mixtureinto. contact with a heated catalytic substance in the presence of anexcess of nitrogen, and separating out the methane.

In testimony, whereof, we affix our signatures in presence'of twowitnesses.

Witnesses:

W. TRIGGS, BERTRAM 'H. MA'rrBnWs.

